1. Field of the Inventions
The present inventions generally relate to an outboard motor that provides a thrust to a watercraft by rotating a propeller using engine power, and more particularly, to an improvement of a shift shaft rotating mechanism to facilitate highly accurate and well-executed shifting of a propeller between neutral, forward, and reverse rotating directions.
2. Description of the Related Art
Japanese Patent Application Publication Nos. JP-A-Hei 5-24580, JP-A-Hei 10-184402, JP-A-2001-65536, JP-A-2004-243934, JP-A-2004-244003, JP-A-2004-245350, and JP-A-2005-297785 each describes an outboard motor that is mounted on the stern of a hull and provides thrust to a watercraft by rotating a propeller using engine driving power. The engine is disposed in an upper portion of the outboard motor, and drives the propeller disposed in a lower portion of the outboard motor through a drive shaft and a propeller shaft. The drive shaft extends vertically downward from the engine. The propeller shaft extends horizontally rearward to the propeller. A shifting device that transmits a driving force from the drive shaft to the propeller shaft is provided between the drive shaft and the propeller shaft (in particular, see Japanese Patent Application Publication Nos. JP-A-2001-65536 and JP-A-2005-297785).
Typically, the shifting device includes a forward bevel gear and a reverse bevel gear, both being provided on the outer surface of the propeller shaft. As the shift shaft rotates, one of the bevel gears meshes with a gear on a lower end of the drive shaft, or both of the bevel gears separate from the gear on the lower end of the drive shaft, thereby performing gear shifting to one of the forward, neutral, and reverse positions. The engine is mounted on the exhaust guide (e.g., reference numeral 28 of JP-A-Hei 5-24580), and the engine is covered with a top cowling.
JP-A-2005-297785 also describes an outboard motor having a shift actuator for rotating a shift shaft (see paragraph [0050] and FIG. 4 of JP-A-2005-297785). The shift actuator swings a shift arm with a driving power of a motor, and also advances and retracts a shift slider using a link rod that is placed between the shift slider and the shift shaft. In this regard, the shift slider advances and retracts the link rod to rotate the shift shaft.